Two-dimensional molybdenum carbide(MXene)as an efficient nanoadditive for achieving superlubricity under ultrahigh pressure

In this study,a robust macroscale liquid superlubricity with a coefficient of friction of 0.004 was achieved by introducing molybdenum carbide(Mo_(2)CT_(x))MXene nanoparticles as lubricating additives in a lithium hexafluorophosphate-based ionic liquid at Si_(3)N_(4)-sapphire interfaces.The maximal contact pressure in the superlubricity state could reach 1.42 GPa,which far exceeds the limit of the superlubricity regime in previous studies.The results indicate that a composite tribofilm(mainly containing molybdenum oxide and phosphorus oxide)that formed at the interface by a tribochemical reaction contributed to the excellent antiwear performance.Furthermore,the extremely low shear strength of the tribofilm and the interlayers of Mo_(2)CT_(x)MXene contributed to the superlubricity.This work demonstrates the promising potential of Mo_(2)CT_(x)MXene in improving superlubricity properties,which could accelerate the application of superlubricity in mechanical systems.

Synthesis of Mo_(2)C MXene with high electrochemical performance by alkali hydrothermal etching

Two-dimensional MXenes are generally prepared by the etching of acid solutions.The as-synthesized MXenes are terminated by acid group anions(F^(–),Cl^(–),etc.),which affect the electrochemical performance of MXenes.Here,we report a novel method to prepare Mo_(2)C MXene from Mo_(2)Ga_(2)C by the hydrothermal etching of alkali solutions.Highly pure Mo_(2)C MXene was successfully synthesized by the etching of NaOH,while the etchings of LiOH and KOH were failed.The concentration of NaOH,temperature,and time strongly affect the purity of as-prepared MXene.Pure Mo_(2)C MXene could be synthesized by the etching of 20 M NaOH at 180 for 24 h.After℃intercalation by hexadecyl trimethyl ammonium bromide at 90 for 96 h,few℃-layer Mo_(2)C MXene was obtained.The Mo_(2)C MXene made by NaOH etching after intercalation exhibited excellent performance as anode of lithium-ion battery,compared with general Mo_(2)C MXene made by HF etching and the Mo_(2)C MXene reported in literature.The final discharge specific capacity was 266.73 mAh·g^(−1)at 0.8 A·g^(−1),which is 52%higher than that Mo_(2)C made by HF etching(175.77 mAh·g^(−1)).This is because Mo_(2)C MXene made by NaOH etching has lager specific surface area,lower resistance,and pure O/OH termination without acid anion termination.This is the first report to make Mo_(2)C MXene by alkali etching and the samples made by this method exhibited significantly better electrochemical performance than the samples made by general HF etching.

Combined obeticholic acid and apoptosis inhibitor treatment alleviates liver fibrosis

Obeticholic acid(OCA), the first FXR-targeting drug, has been claimed effective in the therapy of liver fibrosis. However, recent clinical trials indicated that OCA might not be effective against liver fibrosis, possibly due to the lower dosage to reduce the incidence of the side-effect of pruritus. Here we propose a combinatory therapeutic strategy of OCA and apoptosis inhibitor for combating against liver fibrosis. CCl4-injured mice, D-galactosamine/LPS(GalN/LPS)-treated mice and cycloheximide/TNFα(CHX/TNFα)-treated HepG2 cells were employed to assess the effects of OCA, or together with IDN-6556, an apoptosis inhibitor. OCA treatment significantly inhibited hepatic stellate cell(HSC)activation/proliferation and prevented fibrosis. Elevated bile acid(BA) levels and hepatocyte apoptosis triggered the activation and proliferation of HSCs. OCA treatment reduced BA levels but could not inhibit hepatocellular apoptosis. An enhanced anti-fibrotic effect was observed when OCA was co-administrated with IDN-6556. Our study demonstrated that OCA inhibits HSCs activation/proliferation partially by regulating BA homeostasis and thereby inhibiting activation of HSCs. The findings in this study suggest that combined use of apoptosis inhibitor and OCA at lower dosage represents a novel therapeutic strategy for liver fibrosis.

Molecular engineering tuning optoelectronic properties of thieno[3,2-b]thiophenes-based electrochromic polymers

Thieno[3,2-b]thiophene(TT)monomers end-capped with 3,4-ethylenedioxythiophene(EDOT)moieties are electropolymerized to formπ-conjugated polymers with distinct electrochromic(EC)properties.Steric and electronic factors(electron donor and acceptor substituents)in the side groups of the TT core,as well as the structure of the polymer backbone strongly affect the electrochemical and optical properties of the polymers and their electrochromic characteristics.The studied polymers show low oxidation potentials,tunable from-0.78 to+0.30 V(vs.Fc/Fc^+)and the band gaps from 1.46 to 1.92 eV and demonstrate wide variety of color palettes in polymer films in different states,finely tunable by structural variations in the polymer backbone and the side chains.EC materials of different colors in their doped/dedoped states have been developed(violet,deep blue,light blue,green,brown,purple-red,pinkish-red,orange-red,light gray,cyan and colorless transparent).High optical contrast(up to 79%),short response time(0.57-0.80 s),good cycling stability(up to 91%at 2000 cycles)and high coloration efficiency(up to 234.6 cm2C^(-1))have been demonstrated and the influence of different factors on the above parameters of EC polymers have been discussed.